1. Field of the Invention
The present disclosure relates to methods, devices, and/or systems for delivering therapies and sensing biologic activities via oral appliances in the mouth, in particular for stimulating and sensing tongue activity during sleep, and including in particular for treating sleep disorder breathing, including but not limited conditions of obstructive sleep apnea, snoring, or mild sleep apnea.
2. Background and Description of Related Art
Snoring, which is very common among humans, is a noise produced while breathing during sleep as a result of certain conditions within the body. In most cases, snoring results from vibration of the soft palate and uvula. Snoring often involves a displacement of the tongue from its rest position as well as breathing through the mouth resulting from the abnormal positioning and functioning of the tongue. Snoring can be reduced if the tongue is drawn forward to a more normal position (e.g., in contact with the anatomical folds or wrinkles (rugae) or the mucosa of the anterior palatal region of the mouth. When in an abnormal position, the tongue leaves a space for the passage of air between the hard palate and the top of the tongue and over the soft palate. The passage of air over the soft palate can cause vibrations which are the source behind the snoring sound.
While some degree of snoring is tolerable and has no significant adverse consequence, a common problem is that, on its own, snoring can disturb the sleep of others near the snoring individual. As a result, snoring can result in a diminished ability to remain attentive on both the individual snoring as well as others whose sleep might be adversely affected by the snoring party. As a result, even moderate snoring can result in a reduction in work efficiency and lead to a higher risk of industrial and driving accidents.
A more serious sleep disorder can result from symptomatic, repeated upper airway obstruction during sleep, commonly referred to as Obstructive Sleep Apnea (OSA). “Apnea” is a Greek word meaning without breath. Individual suffering from sleep apnea literally stop breathing in their sleep. It is not uncommon for the incidence of apnea events to occur hundreds of times during the night.
In a given night, the number of involuntary breathing pauses or “apneic events” could be as high as 20 to 60 or more per hour. These breathing pauses are almost always accompanied by snoring between apnea episodes. Sleep apnea can also be characterized by choking sensations. Ingestion of alcohol and sleeping pills increases the frequency and duration of breathing pauses in people with sleep apnea.
30-40% of OSA patients cannot tolerate first-line treatment (such as continuous positive airway pressure, CPAP. Accordingly individuals may consider other options including oral appliances and surgery. Mandibular repositioning appliances and surgery can offer benefit for selected patients, but such conventional remedies can carry risks such as temporomandibular joint disturbance, changes in dental occlusion, or tooth pain for the former and a wide spectrum of potential complications that includes dysphagia or serious perioperative events including myocardial infarction and death in the latter.
The importance of the tongue in OSA and snoring has been recognized for 30 years, as evidenced by the numerous attempts designed to prevent the tongue from falling backwards or to move it forward actively or passively. Oral appliances and multiple tongue-directed surgeries show some promise, but these remedies carry significant risks and side effects, in addition to potential significant bleeding and impairments of taste, swallowing, or speech. Because of the limitations of available passive treatments, active tongue neuromuscular stimulation techniques were attempted to implant wire electrodes, surface stimulating electrodes and hypoglossal nerve stimulation.
A number of factors contribute to OSA, including dilator muscle activation, pharyngeal anatomy, lung volume, arousal threshold, and ventilatory control, with the former two playing critical roles for most individuals. Upper airway patency relies on pharyngeal dilator muscle tone and changes in lung volume that counteract collapsing forces, principally intraluminal negative pressure generated during inspiration and anatomical narrowing of the airway. Individuals with OSA maintain pharyngeal patency with greater dilator muscle tone (principally demonstrated in the genioglossus muscle, the primary muscle within the tongue) during wakefulness; however, sleep onset results in marked decreases in muscle tone due to the loss of the wakefulness stimulus, in addition to decreases in negative pressure reflex activity and lung volume. The effect of decreased muscle tone is magnified in the presence of tongue enlargement, an anatomical abnormality often seen in OSA, perhaps related to an increase in fat deposition within the tongue base in individuals with greater body mass index.
Additional risk factors for sleep apnea include a family history of sleep apnea, excess weight, a large neck, a recessed chin, male gender, abnormalities in the structure of the upper airway, smoking, and alcohol use. Yet sleep apnea can affect both males and females of all ages, including children and any weight. Sleep apnea disturbs normal sleep patterns and people with sleep apnea often feel very sleepy during the day and their concentration and daytime performance suffer. The consequences of sleep apnea range from annoying to life-threatening. They include symptoms suggesting depression, irritability, sexual dysfunction, learning and memory difficulties, and falling asleep while at work, on the phone, or driving.
Conventional treatment with oral appliances and tongue-directed surgical procedures are based on tongue repositioning and/or size reduction. Novel tongue-directed therapies utilizing direct neuromuscular stimulation and oropharyngeal exercises have demonstrated encouraging initial results, but these approaches continue to be limited by cost, invasiveness, compliance, and/or limited effectiveness.
Untreated sleep apnea patients are 3 times (or more) likely to have automobile accidents. It has been estimated that up to 50 percent of sleep apnea patients have high blood pressure. It has recently been shown that sleep apnea contributes to high blood pressure and other cardiovascular disease. Risk for heart attack and stroke may also increase in those with sleep apnea. Sleep apnea is a common disorder that affects millions of men, women and children and is often undiagnosed. It is estimated that at least ten million Americans have unrecognized sleep apnea
Polysomnography is a test that records a variety of body functions during sleep, such as the electrical activity of the brain, eye movement, muscle activity, heart rate, respiratory effort, air flow, and blood oxygen levels. These tests are used both to diagnose sleep apnea and to determine its severity. The specific therapy for sleep apnea is tailored to the individual patient based on medical history, physical examination, and the results of polysomnography. Traditionally, a therapy for sleep apnea is tailored to the individual patient based on medical history, physical examination, and the results of polysomnography.
Medications are generally not effective in the treatment of sleep apnea. While oxygen is sometimes used in patients with central apnea caused by heart failure, it is not used to treat obstructive sleep apnea. Some of the therapies include the use of Provent®, Breatherite® strip, Oral appliances that advance the mandible, continuous positive airway pressure (CPAP), or maxillomandibular advancement surgery, etc. However, some therapies may be partially or completely ineffective in addressing both snoring and/or OSA.
Recently Inspire Medical, Imthera Medical, Apnex Medical and others have been exploring ways of stimulating tongue, tongue muscle or nerves that control the tongue by implanting electrodes in the tongue to deliver electrical signals for stimulation. However, titrating safe levels of stimulation that does not disturb sleep for each patient is a challenge. Others have explored ways of stimulating the tongue base by making the patients wear oral devices. The challenge has been the same.
Given the limitations of current therapies, there is an enormous unmet need for effective, well-tolerated, safe, and minimally invasive OSA treatments. There also remains a need for reducing the incidence of snoring and/or sleep apena that does not require significant physical and/or surgical intervention on the patient. In the article, “Impaired swallowing reflex in patients with obstructive sleep apnea syndrome” (CHEST 1999; 116:17-21), Teramoto et al. published their findings that twenty (20) patients with obstructive sleep apnea also had a compromised swallowing function due to reduced upper airway muscle functions. From this study, one can conclude that increasing the swallowing frequency during sleep could result in increased upper airway muscle functions, and thus potentially reduce or eliminate snoring and obstructive sleep apnea.
In view of the above, there remains a need for an effective, safe, and noninvasive device, for use by itself or during administration of CPAP. The devices, methods and procedures described herein induce a biological response within a mouth, such as promoting tongue neuromuscular activation and anterior tongue displacement to reduce airway obstruction. Additional variations of methods, devices, and systems described herein can also increase salivation and reduce or eliminate snoring and obstructive sleep apnea by one or more of the following: stimulating swallowing, improving muscle tone and increasing frequency of swallowing.